Actuators are used for a variety of functions on seagoing vessels. For example, actuators are used to control the position and/or attitude of a seagoing vessel by manipulation of the vessels control surfaces, including, for example, rudders, tail planes, fore planes, stabilisers and the like. Typically, mechanical or hydraulic actuators are used to manipulate the control surfaces of larger vessels; hydraulic actuators being used, for example, due to their flexibility and the ability to remotely operate the relevant control surface.
Control surfaces in larger vessels may be of significant mass and the actuators must be capable of providing significant force in order to provide precise control over the movement of the control surface, for example, to overcome hydrodynamic forces in moving the control surface against a water flow, wave or the like.
In addition to manipulation of control surfaces, actuators may also be used to deploy and retrieve sensor arrays, telecommunication antennae, mast assemblies or other components or assemblies.
A control surface, component or assembly to be manipulated is often provided in a relatively exposed location on the vessel and it is common that the component will be subject to impacts, for example, from fluid forces or from physical impact of an object.
Furthermore, during operation the control surface, component or assembly may be submerged, or located in another inaccessible location on the vessel, such that damage to a respective component or assembly may severely limit the operational effectiveness of the vessel.